1. Field of the Invention
The present invention relates to a light emitting device and a method of fabricating the same, and more particularly, to a light emitting device having a zener diode therein and a method of fabricating the light emitting device.
2. Discussion of the Background
A light emitting diode is an electroluminescence device that emits light using a forward current. Compound semiconductors, such as InP, GaAs and GaP, have been used as materials of light emitting diodes that emit red or green light. GaN-based compound semiconductors have been developed and used as materials of light emitting diodes that emit ultra violet rays and blue light.
Light emitting diodes have been widely used for various kinds of displays, backlights and the like. Recently, there have been developed techniques for emitting white light by utilizing three light emitting diode chips respectively emitting red, green and blue light or by converting a wavelength using phosphors. Thus, the applications of the light emitting diodes are expanded even to illumination apparatuses.
Generally, a GaN-based compound semiconductor is epitaxially grown on a sapphire substrate of which a crystal structure and a lattice coefficient are similar to those of the GaN-based compound semiconductor, in order to reduce the occurrence of a crystal defect. Since sapphire is an insulating material, electrode pads of a light emitting diode are formed on a growth surface of an epitaxial layer. However, in a case where a substrate made of an insulating material such as sapphire is used, it is difficult to prevent electrostatic discharge due to static electricity introduced from the outside of the light emitting diode, and thus, a diode may be easily damaged, resulting in deterioration of the reliability of the device. Therefore, when packaging a light emitting diode, an additional zener diode is mounted and used together with the light emitting diode in order to prevent electrostatic discharge. However, since a zener diode is expensive and processes of mounting the zener diode are added, the number of processes of packaging a light emitting diode and fabrication costs thereof are increased.
Further, since sapphire has low thermal conductivity, it cannot easily dissipate heat produced from a light emitting diode to the outside. Such low heat dissipation performance makes it difficult to apply light emitting diodes to a field in which a high luminous power is required.
Meanwhile, a transparent electrode layer is generally formed to supply a current to a light emitting diode. Although Ni/Au or ITO transparent electrode layer is generally used, the thickness of each of the transparent electrode layers is limited to about 0.005 to 0.2 μm due to limitations on their light transmission properties. Such a thickness limitation makes it difficult to variously design the configuration of the transparent electrode layer. As a result, it is difficult to obtain uniform light distribution.